Linux where are environment variables stored

Question

If I type into a terminal   export DISPLAY  0 0       where is the shell storing that environment variable   I m using Ubuntu 8 10  I ve looked in the files    profile and  etc profile and can find no trace of DISPLAY

User · Accepted Answer

The environment variables of a process exist at runtime, and are not stored in some file or so. They are stored in the process's own memory (that's where they are found to pass on to children). But there is a virtual file in

/proc/pid/environ

This file shows all the environment variables that were passed when calling the process (unless the process overwrote that part of its memory — most programs don't). The kernel makes them visible through that virtual file. One can list them. For example to view the variables of process 3940, one can do

cat /proc/3940/environ | tr '\0' '\n'

Each variable is delimited by a binary zero from the next one. tr replaces the zero into a newline.

User · Answer

It s stored in the process  shell  and since you ve exported it  any processes that process spawns   Doing the above doesn t store it anywhere in the filesystem like  etc profile   You have to put it there explicitly for that to happen

User · Answer

Type  set  and you will get a list of all the current variables  If you want something to persist put it in    bashrc or    bash profile  if you re using bash

User · Answer

If you want to put the environment for system-wide use you can do so with  etc environment file

User · Answer

That variable isn t stored in some script  It s simply set by the X server scripts  You can check the environment variables currently set using set

[linux] Linux: where are environment variables stored?

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